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| 1 | Vegetation composition differentiation and species-environment relationships in the northern part of Isfahan Province, Iran显示文摘A considerable proportion of Iran's territory is covered with arid and semi-arid rangelands and mismanagement and overexploitation of those rangelands have resulted in serious ecological degradation. Thus, the need is pressing to examine the present species composition and the relationships with environmental factors for providing the needed scientific references to species conservation and ecological rehabilitation efforts. The aims of this study were to examine the species composition and to delineate the most important factors influencing the distributions of plant species and groups in the northern rangelands of Isfahan Province(Iran) using two-way indicator species analysis(TWINSPAN), detrended correspondence analysis(DCA), principal component analysis(PCA), and canonical correspondence analysis(CCA). Field investigations were conducted in the growing season of 2014 using stratified random method in 22 homogeneous sampling units. In total, 75 plant species belonging to 52 genera and 19 families were identified. The most important families were Asteraceae and Papilionaceae, the most important genera were Astragalus, Cousinia, and Acanthophyllum, and the most important species were Artemisia aucheri and Artemisia sieberi. Plant species were classified into 10 groups using TWINSPAN. DCA was used to estimate the magnitude of changes in species composition along the first two ordination axes to provide gradient length estimations for PCA and CCA ordinations. The first three PCA axes and the first three CCA axes demonstrated similar cumulative percentage of variance, indicating that the environmental factors(selected by PCA) used in CCA ordination were acceptable for explaining the species composition and the distributions. CCA ordination showed that the first axis was closely related to elevation, slope, surface bare soil cover, surface litter cover, gravel proportion, organic matter, total nitrogen, Ca CO3 content, and grazing intensity and that the second axis was closely related to sand proportion, silt proportion, clay proportion, and saturation percentage. Among these factors, elevation was the most effective factor to separate the plant groups and grazing was the major cause of rangeland degradation. | Hadi KARGAR-CHIGANI Seyed Akbar JAVADI Ghavamodin ZAHEDI-AMIRI Seyed Jamaleddin KHAJEDDIN Mohamad JAFARI | 2017 | Journal of Arid Land2017，9，2： | 7 |
| 2 | 防潮堤坝对山东昌邑滨海湿地植物及土壤性质的影响分析显示文摘为研究防潮堤坝对滨海湿地植物及土壤性质的影响,本研究在昌邑国家级海洋生态特别保护区内,通过样线法进行野外调查采样,进行防潮堤坝内外土壤、植被以及两者之间联系的分析,研究了堤坝内外植被及土壤性质差异。结果表明:堤坝内外土壤、植被有一定的差异;堤坝外部土壤C、N、P含量小于堤坝内部,堤坝外部土壤盐度大于堤坝内部;堤坝外部是以盐地碱蓬(Suaeda salsa)和獐毛(Aeluropus sinensis)为主滨海湿地景观,堤坝内部则是以柽柳(Tamarix chinensis)为主的灌草丛景观;保护区内物种丰富度与土壤盐度值呈负相关关系,随着盐度的升高,堤坝外部物种丰富度低于堤坝内部;芦苇(Phragmites australis)体内TC、TN、TP及C︰N︰P与土壤C、N、P含量及C︰N︰P没有明显相关性,而柽柳体内N含量与土壤P含量呈明显负相关关系,说明木本植物比草本植物更加依赖土壤中营养元素的供给。 | 陈琤 刘玉虹 陆滢 王光美 张华 | 2017 | 海洋科学2017，41，5： | 3 |
| 3 | Geochemical characterization of the salinity of irrigated soils in arid regions(Biskra, SE Algeria)显示文摘The agriculture in Biskra,southeastern Algeria,is based on traditional practices and characterized by small irrigated fields.In the last decades,the increasing demand in water as well as the scarcity of rainfall has forced many farmers to use groundwater of low quality to maintain the profitability of their crops.Unfortunately,this practice seems to be the main harmful factor for soil quality in the region since it is responsible for the salinization of the irrigated areas.Aiming to assess the impact of this phenomenon,the soils of the irrigated perimeter of El Ghrous-a representative rural community located in the west of Biskra-have been analyzed.A set of 82 soil samples was collected from top and subsoil(0-15 and15-35 cm respectively),on which the following physicochemical analyzes were performed:Ca^(2+),Mg^(2+),K^(+),Na^(+),Cl^(-),SO_(4)^(2-),HCO_(3)^(-),NO_(3)^(-),pH,electrical conductivity(EC)and sodium adsorption ratio.A Principal Component Analysis was performed to individuate the geochemical processes that influenced significantly the evolution of soil salinity and its pathways.The results showed a calcium sulfate(CaSO_(4))facies with a high risk of salinity and a low to medium risk of alkalinity.The calcite residual alkalinity and generalized residual alkalinity decreased as the solutions became more concentrated.Most of the samples were oversaturated in carbonate minerals(aragonite,calcite,and dolomite)and under saturated in evaporitic minerals(anhydrite,gypsum,and halite).Finally,two multiple linear regressions(using cations and anions as independent variables)have been proposed to quantify soil salinity.These equations,with an accuracy of 85%,can represent a time and money-saving tool for managers and farmers to estimate the EC,in comparison to the traditional estimation methods. | Mohamed Amine Abdennour Abdelkader Douaoui Jesus Barrena Manuel Pulido Abdelhamid Bradai Amel Bennacer Chiara Piccini Alberto Alfonso-Torreno | 2021 | Acta Geochimica2021，40，2： | 2 |
| 4 | Interactions between vegetation dynamic and edaphic factors in the Great Salt Desert of central Iran显示文摘Investigating the relationships between vegetation dynamic and edaphic factors provide management insights into factors affecting the growth and establishment of plant species and vegetation communities in saline areas.The aim of this study was to assess the spatial variability of various vegetation communities in relation to edaphic factors in the Great Salt Desert,central Iran.Fifteen vegetation communities were identified using the physiognomy-floristic method.Coverage and density of vegetation communities were determined using the transect plot method.Forty soil samples were collected from major horizons of fifteen profiles in vegetation communities,and analyzed in terms of following soil physical and chemical characteristics:soil texture,soluble Na+concentration,sodium adsorption ratio(SAR),electrical conductivity(EC),pH,organic matter content,soluble Mg2+and Ca2+concentrations,carbonate and gypsum contents,and spontaneously-and mechanically-dispersible clay contents.Redundancy analysis was used to investigate the relationships between vegetation dynamic and edaphic factors.The generalized linear method(GLM)was used to find the plant species response curves against edaphic factors.Results showed that plant species responded differently to edaphic factors,in which soluble sodium concentration,EC,SAR,gypsum content and soil texture were identified as the most discriminative edaphic factors.The studied plant species were also found to have different ecological requirements and tolerance to edaphic factors,in which Tamarix aphylla and Halocnemum strobilaceum were identified as the most salt-resistant species in the region.Furthermore,the presence of Artemisia sieberi was highly related to soil sand and gypsum contents.The results implied that exploring the plant species response curves against edaphic factors can assist managers to lay out more appropriate restoration plans in similar arid areas. | Hossein BASHARI Seyed Mehrdad KAZEMI Soghra POODINEH Mohammad R MOSADDEGHI Mostafa TARKESH Seyed Mehdi ADNANI | 2021 | Journal of Arid Land2021，13，2： | 0 |
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